The present invention relates to a transverse positioning device for stabilizing bars, which can easily be applied thereto, is effective and can easily be produced at reasonable cost. The invention also relates to a stabilizing bar equipped with such a device and to a stabilization system for vehicles making use of such a device.
The stabilizing bar, also known as "anti-roll bar", is a flexible component of the front and rear suspension of a motor vehicle, the function of which is to limit lateral oscillations and roll, contributing to improvements in "driving comfort" and roadholding. For each axle (pair of front wheels and pair of rear wheels) one or more bars are provided which connect together the wheel arms by which the other components of the suspension (helical springs, leaf springs, shock absorbers etc.) are supported. Each bar is secured to the body by means of two central supports, comprising rubber or rubber/metal bushes locked by metal clips of connection to the body, which do not usually permit the rotation of the bar inside the support nor its axial sliding, insofar as the compressed rubber adheres intimately to the bar, thus locking it.
In use, the bar, which is usually of trapezoidal shape (although it may also have a very complex shape) reacts with flexo-torsional stresses; the optimization of the stabilizing function aims to cause the bar to operate exclusively under torsion without inducing undesired components on the supports anchored to the vehicle chassis (body), and to have the highest possible speed of response on the passenger compartment. However, because of the anchoring system described, in use the rubber of the supports is required to operate under torsion also, and this produces a flexible chain formed not only by the steel of the bar but also by the rubber of the supports: the flexibility of the system is consequently increased, with a negative influence on the speed of response of the stabilization system.
To overcome this disadvantage the use has been proposed of stabilization systems in which the bar is connected to the vehicle chassis/body by means of supports equipped with anti-friction sleeves which thus permit, under torsional stresses, the free rotation of the bar with respect to the flexible sleeve without the latter being subject to torsional stress in its turn. However, the systems of this type have the problem of how to keep the bar in transverse position insofar as, thanks to the above-mentioned sleeves, not only is the bar free to rotate but also to travel with respect to the supports.
A first solution provides the production, in the vicinity of the supports, of bends in the bar such as to form elbows which act as stops: this solution does, however, have the disadvantage of creating in the bar appreciable bending stresses which reduce its stabilization efficiency and speed. A second solution, provided by international application No. WO91/09748, comprises co-moulding a plastic or rubber stop element on the bar: this element, once injection-moulded onto the external surface of the bar, should be axially locked onto it by the effect of the radial compression consequent upon the phenomenon of "contraction" (reduction of volume resulting from the solidification of the injected material) being thus able to act as a shoulder. This solution is not, however, entirely reliable because of critical ambient conditions (temperature, ozone, oils etc.) and, on the other hand, is extremely expensive in that the co-moulding requires injection presses and equipment that are extremely large, costly and cumbersome, because of the generally large dimensions of the bar (from 40-100 cm up to more than 1 meter) furthermore, with significant modifications to the normal production flows.